Process for preparing tris[3-(alkyldialkoxysilyl)propyl]isocyanurates

ABSTRACT

A process can prepare an isocyanurate compound by hydrosilylation. The compound is a tris[3-(trialkoxysilyl)propyl] isocyanurate, a tris[3-(alkyldialkoxysilyl)propyl] isocyanurate, and/or a tris[3-(dialkylalkoxysilyl)propyl] isocyanurate, The process includes (A) preparing a mixture of at least one carboxylic acid, a platinum catalyst, and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; (B) heating the mixture to a temperature in the range of 40 to 140° C.; (C) adding at least one H-silane among a hydrotrialkoxysilane, a hydroalkyldialkoxysilane, and a hydrodialkylalkoxysilane to the mixture; (D) adding at least one alcohol to the mixture prepared in step (C); and (E) isolating the isocyanurate compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/159,763, filed on Oct. 15, 2018, which is pending, which is hereinincorporated by reference in its entirety, and which is acontinuation-in-past of U.S. application Ser. No. 15/915,126, filed Mar.8, 2018, which issued as U.S. Pat. No. 10,125,156 on Nov. 13, 2018, andwhich is herein incorporated by reference in its entirety, and claimspriority to European Patent Office Application 17159900.4, filed Mar. 8,2017, which is herein incorporated by reference in its entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-n-part of U.S. application Ser. No.15/915,128, lied Mar. 8, 2018, which is pending, and which is hereinincorporated by reference in its entirety, and claims priority toEuropean Patent Office Application 17159900.4, led Mar. 8, 2017, whichis herein incorporated by reference in is entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a particularly economically viableprocess for preparing tris[3-(trialkoxysilyl)propyl] isocyanurate,tris[3-(alkyldialkoxysilyl)propyl] isocyanurate andtris[3-(dialkylalkoxysilyl)propyl] isocyanurate (also referred tocollectively hereinafter as tris[3-(alkoxysilyl)propyl] isocyanuratesfor short), wherein 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trioneis hydrosilylated with a hydrotrialkoxysilane, hydroalkyldialkoxysilaneor hydrodialkylalkoxysilane in the presence of a Pt catalyst, acarboxylic acid and a further cocatalyst.

Tris[3-(alkoxysilyl)propyl] isocyanurates are silanes that can be usedas crosslinkers. By virtue of the three alkoxysilyl groups, of whicheach alkoxysilyl group after hydrolysis can enter into one, two or threechemical bonds, three up to nine chemical bonds are theoreticallypossible. By virtue of these significant crosslinking opportunities,tris[3-(alkoxysilyl)propyl] isocyanurates are of interest for variousapplications. A further advantage of tris[3-(alkoxysilyl)propyl]isocyanurates is the high thermal stability that enables use in thehigh-temperature range. Tris[3-(alkoxysilyl)propyl] isocyanurates cantherefore be used advantageously as crosslinker, for example, in paintand rubber formulations and as adhesion promoter in paints and adhesivesin a wide variety of different industries. The high crosslinking densityadditionally allows production of scratch-resistant coatings and barrierlayers.

Description of the Related Art

JP4266400B describes the preparation of an aromatic silane compound byhydrosilylation of an aromatic vinyl compound. The catalyst used is aplatinum complex in the presence of a carboxylic acid.

U.S. Pat. No. 5,986,124 relates to a process for preparing a silanecompound by hydrosilylation of a carbon double bond by means of atrialkoxyhydrosilane in the presence of a platinum catalyst and acarboxylic acid. Through the use of platinum catalysts together withcarboxylic acids, it is possible to achieve a conversion of about 80% inthe hydrosilylation, but crude products thus obtained still include aconsiderable proportion of impurities and/or by-products.

EP 0587462 describes a composition composed of an unsaturatedpolyorganosiloxane, an organohydropolysiloxane, an acid, a platinumcompound and additives, wherein the components are emulsified in waterand used for surface release treatment. The crosslinking is effected viahydrosilylation in the course of heating.

EP 0856517 discloses a process for hydrosilylation of an unsaturatedcompound in the presence of a metal compound of transition groups 8 to10 of the Periodic Table of the Elements. The hydrosilylation isconducted in the presence of an accelerator.

EP 1869058/WO 2006/113182 presents a process for preparingtris[3-(trialkoxysilyl)propyl]socyanurate. The preparation proceeds viathe cracking of silyl organocarbamate in the presence of a catalyticamount of a carboxylate salt.

EP 0583581 teaches the preparation of a silyl organocarbamate from anaminosilane. The silyl organocarbamate is subsequently converted to thesilyl isocyanurate in the presence of a “cracking catalyst”.

EP 1885731 discloses a process for preparing isocyanatosilanes and silylisocyanurate. The synthesis starts with a silyl organocarbamate. Bycatalytic cracking, the isocyanatosilane is released, and the conversionof the isocyanatosilane to the silyl isocyanurate is effected in atrimerization reaction zone.

CA 943544 describes the preparation of a silyl organoisocyanurate from ahaloalkylsilane and a metal cyanate in the presence of a solvent. Thesolvent and the salt formed are removed after the reaction.

U.S. Pat. No. 3,607,901 relates to the preparation of isocyanatosilanesand isocyanuratosilanes proceeding from chloroalkyltrialkoxysilanes anda metal cyanate.

U.S. Pat. No. 3,517,001 teaches, inter alia, the preparation of1,3,5-tris(trimethoxysiylpropyl) isocyanurate by hydrosilylation of1,3,5-tris(allyl isocyanurates) with trimethoxysilane in the presence ofhexachloroplatinic acid. The yield is reported as 40%.

U.S. Pat. No. 3,821,218 describes the preparation of1,3,5-tris(trimethoxysilylpropyl) isocyanurate proceeding fromchloropropyltrimethoxysilane and potassium cyanate in DMF as solvent.

US 2013/0158281 discloses a process for hydrosilylation of anunsaturated compound with a silyl hydride. The catalysts used are Fecomplexes, Ni complexes, Mn complexes or Co complexes.

CN 101805366 describes the preparation of1,3,5-tris(trimethoxysilylpropyl) isocyanurate by cyclocondensation ofisocyanatopropytrimethoxysilane.

CS 195549 relates to the hydrosilylation of vinylcyclohexane withhydrosilanes. In example 4, vinylcyclohexane is hydrolysed by means oftriethoxysilane in the presence of platinic acid and trifluoroaceticacid.

BRIEF SUMMARY OF THE INVENTION

The problem addressed by the present invention was that of providing aprocess for preparing tris[3-(alkoxysilyl)propyl] isocyanurates, i.e.from the group of tris[3-(trialkoxysilyl)propyl]isocyanurate,tris[3-(alkyldialkoxysilyl)propyl] isocyanurate andtris[3-(dialkylalkoxysilyl)propyl]isocyanurate, where alkyl isespecially—but not exclusively—methyl or ethyl and alkoxy is methoxy orethoxy, in which a Pt catalyst is used in conjunction with a carboxylicacid and the disadvantages detailed above are reduced if possible via acontrolled reaction regime, specific feed ratios and/or furtheradditions. Furthermore, another aim was, if possible, to conduct theprocess with a minimum concentration of costly platinum and without theseparate addition of an aliphatic or aromatic solvent and to increasethe yield of target product. It was also desirable to keep the contentof carboxylic acid remaining in the target product to a minimum.

The problem is solved according to the present claims.

It has been found that, surprisingly, significantly better yields oftarget product, i.e. a tris[3-(alkoxysilyl)propyl] isocyanurate, areachieved when the hydrosilylation is performed by

-   -   in step A initially charging a mixture comprising        1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione as olefin        component, at least one carboxylic acid and a Pt catalyst,        heating the mixture to a temperature of 50 to 140° C.,    -   in step B adding at least one hydroalkoxysilane from the group        of hydrotrialkoxysilane, hydroalkyldialkoxysilane,        hydrodialkylalkoxysilane [called H-silane(s) for short] to the        mixture from step A while mixing,    -   in step C leaving the mixture from step B to react while mixing,        with addition of at least a defined amount of alcohol to the        mixture as further cocatalyst, and    -   in step D working up the product mixture thus obtained        and so the reaction and the selectivity and hence the yield of        the hydrosilylation is markedly promoted.

In an embodiment 1, a process for preparing atris[3-(alkoxysilyl)propyl] isocyanurate from the group oftris[3-(trialkoxysilyl)propyl] isocyanurate,tris[3-(alkyldialkoxysilyl)propyl] isocyanurate andtris[3-(dialkylalkoxysilyl)propyl] isocyanurate by hydrosilylation,includes

-   -   in step A initially charging a mixture comprising        1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione as olefin        component, at least one carboxylic acid and a Pt catalyst,        heating the mixture to a temperature of 40 to 140° C.,    -   in step B adding at least one hydroalkoxysilane from the group        of hydrotrialkoxysilane, hydroalkyldialkoxysilane,        hydrodialkylalkoxysilane [called H-silane(s) for short] to the        mixture from step A while mixing,    -   in step C leaving the mixture from step B to react while mixing,        with addition of at least a defined amount of alcohol to the        mixture as further cocatalyst, and    -   in step D working up the product mixture thus obtained.

In an embodiment 2, is the process according to embodiment 1,characterized in that H-silane is used relative to alcohol in a molarratio of 1:0.005 to 0.3, preferably 0.01 to 0.2, preferably 1:0.02 to0.18, more preferably 1:0.03 to 0.15, even more preferably 1:0.04 to0.1, especially 1:0.05 to 0.06.

In an embodiment 3, is the process according to embodiment 1 or 2,characterized in that H-silane is used relative to Pt in a molar ratioof 1:1×10⁻⁴ to 1×10⁻⁹, preferably 1:1×10⁻⁵ to 3×10⁻⁸, especially1:1×10⁻⁵ to 9.0×10⁻⁶.

In an embodiment 4, is the process according to any of the precedingembodiments, characterized in that

H-silane is used relative to carboxylic acid in a molar ratio of1:1×10⁻³ to 30×10⁻³, preferably 1:2×10⁻³ to 8×10⁻³.

In an embodiment 5, is the process according to any of the precedingembodiments, characterized in that

H-silane is used relative to olefin component in a molar ratio of 1:0.1to 1, preferably 1:0.2 to 0.4.

In an embodiment 6, is the process according to any of the precedingembodiments, characterized in that

the carboxylic acid is selected from the group of benzoic acid,propionic acid, 2,2-dimethylpropionic acid, 3.5-di-tert-butylbenzoicacid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, acetic acid.

In an embodiment 7, is the process according to any of the precedingembodiments, characterized in that

the alcohol is selected from the group of the C₁-C₁₀ alcohols,preferably from the group of tert-butanol, ethanol, methanol, benzylalcohol and diglycol monomethyl ether.

In an embodiment 8, is the process according to any of the precedingembodiments, characterized in that

the H-silane used is hydrotrimethoxysilane (TMOS), hydrotriethoxysilane(TEOS), methyldiethoxysilane (DEMS), methyldimethoxysilane (DMMS),dimethylethoxysilane (DMES) or dimethylmethoxysilane (MDMS).

In an embodiment 9, is the process according to any of the precedingembodiments, characterized in that

a Pt catalyst from the “Karstedt catalyst” group s used, preferablyplatinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex,especially in the form of “Karstedt catalyst” in xylene or toluene witha Pt(0) content of 0.5% to 5% by weight, hexachloroplatinum(IV) acid,preferably “Speier catalyst”, especially hexachloroplatinum(IV) aciddissolved in acetone, or Pt applied to a solid catalyst support,preferably Pt supported on activated carbon.

DETAILED DESCRIPTION OF THE INVENTION

Any ranges mentioned herein below include al values and subvaluesbetween the lowest and highest limit of this range.

It has been found here to be particularly advantageous that the presentprocess is preferably conducted with a homogeneous platinum(0) complexcatalyst, especially a “Karstedt catalyst”, a “Speier catalyst”,hexachloroplatinum(IV) acid or a supported, i.e. heterogeneous, Ptcatalyst, for example Pt on activated carbon. In addition, a “Karstedtcatalyst” is preferably used in the form of a platinum(0) complexcatalyst solution, especially dissolved in xylene or toluene.

The present procedure also makes it possible to reduce the content of Ptcatalyst/the Pt loss, and hence to save costly Pt. Moreover, it has beenfound to be particularly advantageous in the present process to use acarboxylic acid from the group of benzoic acid, 3,5-di-tert-butylbenzoicacid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, 2,2-dimethylpropionicacid, propionic acid and/or acetic acid.

A product mixture obtained by the present process is suitably worked upby distillation, optionally under reduced pressure, and the desired(target) product is obtained.

In the case of use of a heterogeneous catalyst, the latter can suitablybe separated from the product mixture prior to the distillation, forexample by filtration or centrifugation, and this Pt catalyst thusrecovered can advantageously be recycled into the process.

For instance, the target product is obtained as bottom product in thedistillation conducted after the reaction and, if necessary, after theremoval of a heterogeneous catalyst; the target product is not distilledover in the distilative workup and is obtained as a colourless bottomproduct.

In the present process, the double bonds of the olefin component usedhere can advantageously be virtually completely hydrosilylated,advantageously giving rise to only a very low level of by-products.

Furthermore, the present process, i.e. that according to the invention,can advantageously be conducted without separate addition of analiphatic or aromatic hydrocarbon as solvent or diluent, and with only asmall proportion of the carboxylic acid (co-)catalyst component whichremains in the target product.

The present Invention thus provides a process for preparing atris[3-(alkoxysilyl)propyl]isocyanurate from the group oftris[3-(trialkoxysilyl)propyl] isocyanurate,tris[3-(alkyldialkoxysilyl)propyl] isocyanurate andtris[3-(dialkylalkoxysilyl)propyl] isocyanurate by hydrosilylatlon,

by

-   -   In step A initially charging a mixture comprising        1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione as olefin        component, at least one carboxylic acid and a Pt catalyst,        heating the mixture to a temperature of 40 to 140° C.,    -   in step B adding at least one hydroalkoxysilane from the group        of hydrotrialkoxysilane, hydroalkyldialkoxysilane,        hydrodialkylalkoxysilane [called H-silane(s) for short] to the        mixture from step A while mixing,    -   in step C leaving the mixture from step B to react while mixing,        with addition of at least a defined amount of alcohol to the        mixture as further cocatalyst, and    -   in step D working up the product mixture thus obtained.

In the process according to the invention. H-silane is advantageouslyused relative to olefin component in a molar ratio of 1:0.1 to 1,preferably of 1:0.2 to 0.4, especially—to give just a few of thepossible intermediate values here that will be clear or derivable forthe person skilled in the art from the figures above and the presentfigures, in a representative manner and by way of example—1:0.13,1:0.15, 1:0.18, 1:0.23, 1:0.25, 1:0.28, 1:0.3, 1:0.33, 1:0.35, 1:0.38.

The H-silane used here is preferably hydrotrimethoxysilane (TMOS),hydrotriethoxysilane (TEOS), methyidiethoxysilane (DEMS),methyldimethoxysilane (DMMS), dimethylethoxysilane (DMES) and/ordimethylmethoxysilane (MDMS).

Moreover, in the process according to the invention, the olefincomponent used is 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

Advantageously, in the process according to the invention, it ispreferable to use H-silane relative to alcohol in a molar ratio of1:0.005 to 0.3, preferably 0.01 to 0.2, preferably 1:0.02 to 0.18, morepreferably 1:0.03 to 0.15, even more preferably 1:0.04 to 0.1,especially 1:0.05 to 0.06. Preferably, for this purpose, at least onealcohol is selected from the group of the C₁-C₁₀ alcohols, morepreferably at least one from the group of tert-butanol, ethanol,methanol, benzyl alcohol and diglycol monomethyl ether.

Moreover, in the process according to the invention. H-silane isadvantageously used relative to Pt in a molar ratio of 1:1×10⁻⁴ to1×10⁻⁹, preferably 1:1×10⁻⁵ to 1×10⁻⁸, especially of 1:1×10⁻⁵ to 9×10⁴.

The Pt catalyst used here is suitably a heterogeneous Pt catalyst,preferably Pt applied to a solid catalyst support, especially Pt onactivated carbon, or a homogeneous Pt catalyst, preferably a Pt complexcatalyst, such as hexachloroplatinum(IV) acid, also called “Speiercatalyst”, especially hexachloroplatinum(IV) acid dissolved in acetone,preferably a Pt(0) complex catalyst, more preferably a “Karstedtcatalyst”, even more preferably aplatinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex,especially a “Karstedt catalyst” in xylene or toluene with a Pt(0)content of 0.5% to 5% by weight. Such a solution generally contains aplatinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex dissolvedin xylene or toluene, and a solution used in accordance with theinvention is advantageously used in dilute form and preferably containsa Pt content of 0.5% to 5% by weight. Thus, in the process according tothe invention, it is advantageous to use a Pt catalyst from the group of“Karstedt catalyst”, especially a “Karstedt catalyst” solution,preferably platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexin xylene or toluene with a Pt(0) content of 0.5% to 5% by weight,hexachloroplatinum(IV) acid, preferably “Speier catalyst”, especiallyhexachloroplatinum(IV) acid dissolved in acetone, or Pt supported onactivated carbon.

Further, in the process according to the invention, H-silane ispreferably used relative to carboxylic acid in a molar ratio of 1:1×10⁻³to 30×10⁻³, more preferably 1:1×10⁻³ to 10×10⁻³, especially of 1:2×10⁻³to 8×10⁻³.

For this purpose, the carboxylic acid is preferably selected from thegroup of benzoic acid, 3,5-di-tert-butylbenzoic acid,3,5-di-tert-butyl-4-hydroxybenzoic acid, propionic acid,2,2-dimethylpropionic acid, acetic acid.

It is thus possible, in general, to execute the process according to theinvention—with all its possible combinations of the features detailed inthe present description—as follows:

For the performance of the hydrosilylation according to the inventionfor preparation of a tris[3-(alkoxysilyl)propyl] isocyanurate, a stirredreactor with metering apparatus, heating/cooling apparatus, refluxapparatus and distillation apparatus, suitably under protective gas, forexample nitrogen,

-   -   in step A is initially charged with a mixture comprising        1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione as olefin        component, at least one carboxylic acid, preferably benzoic        acid, 3,5-di-tert-butylbenzoic acid,        3,5-di-tert-butyl-4-hydroxybenzoic acid, propionic acid,        2,2-dimethylpropionic acid and/or acetic acid, and a Pt        catalyst, suitably a “Speier catalyst”, preferably        hexachloroplatinum(IV) acid in acetone or hexachloroplatinum(IV)        acid hexahydrate dissolved in acetone or a “Karstedt catalyst”,        the latter preferably being used in the form of a platinum(0)        complex catalyst solution, or Pt on activated carbon, and the        mixture is heated to a temperature of 40 to 140° C., preferably        to a temperature of 50 to 120° C.,    -   in step B at least one hydroalkoxysilane from the group of        hydrotrialkoxysilane, hydroalkyldialkoxysilane,        hydrodialkylalkoxysilane [called H-silane(s) for short] is added        to the mixture from step A while mixing.    -   In step C the mixture from step B is left to react while mixing,        with addition of at least a defined amount of alcohol to the        mixture as further cocatalyst, preferably under temperature        control and over 1 to 10 or more hours, where the metering time        may clearly be dependent on the batch size and the reactor        design; it is suitably possible to allow further reaction while        mixing, for example at a temperature of 60 to 100° C.,        especially over 0.5 to 2 hours; the alcohol can also be added        separately.    -   in the subsequent step D the product mixture thus obtained is        worked up.

Thus, in present processes, the respective feedstocks are preferablyused in a well-defined molar ratio:

-   -   H-silane to olefin component in a molar ratio of 1:0.1 to 1    -   H-silane to alcohol in a molar ratio of 1:0.01 to 02    -   H-silane to Pt in a molar ratio of 1:1×10⁻⁷ to 1×10⁻⁹.    -   H-silane to carboxylic acid in a molar ratio of 1:1×10⁻³ to        30×10⁻³

In addition, the “Karstedt catalyst” solution used is preferablyprepared from a conventional “Karstedt catalyst” concentrate(platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiioxane complex, platinumcontent: 20.37% by weight) (also called “Karstedt concentrate”hereinafter for short). the concentrate preferably being adjusted to aPt content of 0.5% to 5% by weight by the addition of xylene or toluene.

A product mixture thus obtained is a suitably worked up by distillationto obtain the desired (target) product. For this purpose, thedistillation is preferably conducted commencing at 45° C. to 150° C. anda reduced pressure (vacuum distillation at less than 1 bar and falling,especially not more than 0.1 bar), wherein low boilers that are presentin particular, for example carboxylic acid, alcohol, excess H-silane andany olefin component still present are removed from the product mixture.If a heterogeneous Pt catalyst is used for the performance of theprocess according to the invention, the heterogeneous Pt catalyst can beseparated from the product mixture obtained after the reaction in thecourse of the product workup, i.e. prior to the distillation step, forexample by filtration or centrifugation, and advantageously be recycledback into the process.

It is thus advantageously possible to preparetris[3-(alkoxysilyl)propyl] isocyanurates obtainable in accordance withthe invention in comparatively high yield and selectivity, i.e. withonly small proportions of by-products, even on the industrial scale in asimple and economically viable manner.

The examples which follow provide additional illustration of the presentinvention without restricting the subject-matter:

EXAMPLES

Analytical Methods:

NMR Measurements:

Instrument: Bruker

Frequency: 500.1 MHz (¹H NMR)

Scans: 32

Temperature: 303 K

Solvent: CDCl₃

Standard: 0.5% TMS (tetramethylsilane)

Explanations are given below with regard to naming of target product andby-products formed in the synthesis with respect to the present ¹H NMRevaluations using the example of the structural formula of atris[3-(trialkoxysilyl)propyl] isocyanurate. The determinations ofselectivities with respect to tris[3-(methyldialkoxysilyl)propyl]isocyanurate and tris[3-(dimethylalkoxysilyl)propyl]isocyanurate wereconducted analogously and are listed in the tables for Examples 6 and 7.

in the target product: functional group S1 (Si—CH₂—)

in the so-called allyl derivative: functional group A1

in the so-called propyl derivative: functional group P1

in the so-called isopropyl derivative: functional group I1

The experiments were evaluated using the product formed in thehydrosilylation of the1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. The more allylicdouble bonds were converted to the target product and the fewersecondary components were formed, the better the product quality and theperformance/selectivity of the catalyst system. A high selectivity isvery important because the secondary components can be removed bydistillation from the target product only with a very high level ofcomplexity, if at all.

The 1H NMR spectra were evaluated using the hydrogen atoms included inthe structural formula drawings. The hydrosilylation gives rise toSi—CH₂— groups that are characteristic of the target product. TheSi—CH₂— groups were identified with S1, the allylic groups (C═CH₂—group) with A1, the propyl group (C₃H₇— group) with P1 and the isopropylgroup with I1. The evaluation of the 1H NMR spectra and the calculationof the functional groups was shown after each experiment in the tables.The evaluated signals from the ¹H NMR form triplets (t) for the S1 andP1 group, double doublets (dd) for the A1 group, and doublets (d) forthe 11 group.

Chemicals Used:

“Karstedt concentrate” (platinum(0)1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content:20.37% by weight), HERAEUS

Acetone, pure, LABC Labortechnik

Hexachloroplatinum(IV) acid hexahydrate, platinum content 40% by weight,HERAEUS

Platinum-activated carbon, hydrogenation catalyst, platinum content 10%by weight, MERCK

Benzyl alcohol, puriss, SIGMA ALDRICH

Diethylene glycol monomethyl ether >98% by weight, MERCK

Xylene Technical, VWR Chemicals

Dynasylan® TMOS (trimethoxysilane), EVONIK Industries

Dynasylan® TEOS-H (triethoxysilane). EVONIK Industries

Dynasylan® DEMS (methyldiethoxysilane), EVONIK Industries

Dynasylan® DMES (dimethylethoxysilane), EVONIK Industries

TIACROS® (1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione), EVONIKIndustries

Benzoic acid ≥99.5% by weight, ROTH

3,5-Di-tert-butylbenzoic acid >98.0% by weight, TOKYO CHEMICAL INDUSTRY

3,5-Di-tert-butyl-4-hydroxybenzoic acid, >98.0% by weight, TOKYOCHEMICAL INDUSTRY

Acetic acid, ≥99% by weight, SIGMA-ALDRICH

Methanol ≥99.5% by weight, MERCK

Ethanol ≥99.8% by weight, ROTH

tert-Butanol, ≥99.0% by weight (for synthesis), ROTH

Chloroform-d1 (CDCl₃)+0.5% by weight of TMS, DEUTERO

Benzene-d6, DEUTERO

Tetramethylsilane, DEUTERO

Preparation of “Karstedt-Catalyst” No. 1 with Platinum Content 2% byWeight in Xylene:

In a 0.2 l glass bottle, 9.8 g of “Karstedt concentrate” (platinum(0)1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content20.37%) were mixed with 90.2 g of xylene.

Preparation of “Karstedt-Catalyst” No. 2 with Platinum Content 2% byWeight in Toluene:

In a 0.2 l glass bottle, 9.8 g of “Karstedt concentrate” (platinum(0)1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content20.37% by weight) were mixed with 90.2 g of toluene.

Preparation of “Karstedt-Catalyst” No. 3 with Platinum Content 0.4% byWeight:

In a 0.1 l glass bottle, 196.4 mg of “Karstedt concentrate” (platinum(0)1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content20.37% by weight) were mixed with 9.8 g of toluene.

Preparation of Catalyst 4 from Hexachloroplatinum(IV) Acid HexahydrateSolution in Acetone with Pt Content 2.34% by Weight:

In a 12 l plastic vessel, 530 g of H₂PtCl₆×6H₂O were dissolved in 9.8 lof acetone. The catalyst solution thus prepared was used after maturingfor 8 weeks.

Comment on the Comparative Examples which Follow:

The synthesis in ampoules described in U.S. Pat. No. 5,986,124 cannot beconducted on the industrial scale. In order that the experiments can bebetter compared with the inventive examples, the experiments wereconducted in a stirred tank or flask. Furthermore, in the examples inU.S. Pat. No. 5,986,124, different unsaturated compounds were used, andso a direct comparison with the present invention would not be possible;thus, TAICROS® was used in the comparative examples which follow.

Comparative Example 1: (Based on Example 1 from U.S. Pat. No. 5,986,124)

0.2003 mol (24.5 g) of Dynasylan® TMOS, 0.1 ml of Catalyst No. 1, afurther 40.0 g of toluene as additional solvent/diluent, 0.0665 mol(16.6 g) of TAICROS® and 0.4 ml of acetic acid were initially charged ina 0.25 l stirred apparatus with jacketed coil condenser and stirred inan oil bath heated to 53-55° C. for 2.5 hours. This gave 79.9 g ofincompletely converted and colourless bottom product. The volatilecomponents were not removed.

Evaluation of the ¹H NMR spectrum with regard to Comparative Example 1:

Solvent: N CDCl₃ + 0.5% Signal at Integral Number of TMS [ppm] I protonsI/N % (mol) S1 0.64 100.00 2 50.00 45.8 A1 5.27 117.28 2 58.64 53.7 P10.93 0.81 3 0.27 0.3 I1 1.00 0.61 3 0.20 0.2 Result: 45.8% of the allylgroups were converted by hydrosilylation to trimethoxysilylalkyl groups(cf. S1). 53.7% of the allyl groups (A1) have not been converted, and0.3% propyl groups (P1) and 0.2% isopropyl groups (I1) that contaminatethe product have formed. The reaction is incomplete.

Comparative Example 2: (Based on Example 1 from U.S. Pat. No. 5,986,124)

0.2003 mol (32.9 g) of Dynasylan® TEOS-H, 0.1 ml of Catalyst No. 3, afurther 40.0 g of toluene as additional solvent/diluent, 0.0665 mol(16.6 g) of TAICROS® and 0.4 ml of acetic acid were initially charged ina 0.25 l stirred apparatus with reflux condenser and stirred in an oilbath heated to 50-57° C. for 2.5 hours. This gave 88.2 g of incompletelyconverted and colourless bottom product. The volatile components werenot removed.

Evaluation of the ¹H NMR spectrum with regard to Comparative Example 2:

Solvent: N CDCl₃ + 0.5% Signal at Integral Number of TMS [ppm] I protonsI/N % (mol) S1 0.64 100.00 2 50.00 86.2 A1 5.26 14.59 2 7.30 12.6 P10.94 0.33 3 0.33 0.6 I1 1.06 0.35 3 0.35 0.6 Result: 86.2% of the allylgroups were converted by hydrosilylation to trimethoxysilylalkyl groups(cf. S1). 12.6% of the allyl groups (A1) have not been converted, and0.6% propyl groups (P1) and 0.6% isopropyl groups (I1) that contaminatethe product have formed. The reaction is incomplete.

Comparative Example 3: (with Acetic Acid Only, No Addition of Alcohol)

1.2 mol of DYNASYLAN® TMOS and 02 g of Catalyst No. 1 (corresponding to0.0205 mmol of Pt) were initially charged in a 0.5 l stirred apparatuswith reflux condenser, metering apparatus. At a temperature of 76-91°C., a mixture consisting of 0.33 mol of TAICROS® and 6.77 mmol of aceticacid was metered in within 1 h. Thereafter, the mixture was left toreact further at about 87-92′C for about 1 further hour. Subsequently,55.0 g of low boilers were removed at 90-120° C. and a pressure of <0.1mbar. This gave 170.7 g of incompletely converted, colourless bottomproduct.

Evaluation of the ¹H NMR spectrum with regard to Comparative Example 3:

Solvent: N CDCl₃ + 0.5% Signal at Integral Number of TMS [ppm] I protonsI/N % (mol) S1 0.66 100.00 2 50.00 73.8 A1 5.25 34.79 2 17.40 25.7 P10.94 0.61 3 0.20 0.3 I1 1.01 0.43 3 0.14 0.2 Result: 73.8% of the allylgroups were converted by hydrosilylation to trirnethoxysiylalkyl groups(cf. S1). 25.7% of the allyl groups (A1) have not been converted, and0.3% propyl groups (P1) and 0.2% isopropyl groups (I1) that contaminatethe product have formed. The reaction is incomplete.

Comparative Example 4

1.2 mol of Dynasylan® TMOS, 0.2 g of “Karstedt catalyst” (correspondingto 0.0205 mmol of Pt), 34.38 mmol of methanol and 6.55 mmol of benzoicacid were initially charged in a 0.5 l stirred apparatus with refluxcondenser, metering apparatus. At a temperature of 73-82° C., 0.33 molof TAICROS® was metered in within 1 hour. Thereafter, the mixture wasleft to react further at 81° C. for another 1 hour. Subsequently, 89.5 gof low boilers were removed at 35-127° C. and a pressure of <0.1 mbar.This gave 134.2 g of incompletely converted and colourless bottomproduct.

Evaluation of the ¹H NMR spectrum from Comparative Example 4:

Solvent: N CDCl₃ + 0.5% Signal at Number of TMS [ppm] Integral protonsI/N % (mol) S1 0.66 100.00 2 50.00 42.5 A1 5.25 134.10 2 67.05 57.0 P10.94 1.24 3 0.41 0.4 I1 1.01 0.36 3 0.12 0.1 Result: 42.5% of the allylgroups were converted by hydrosilylation with TMOS totrimethoxysilylalkyl groups (cf. S1). 57.0% of the allyl groups (A1)were not converted. 0.4% propyl groups (P1) and 0.1% isopropyl groups(I1) that contaminate the product were formed. The conversion of theallyl groups is incomplete, and only a low level of by-products isformed.

Comparative Example 5

1.2 mol of Dynasylan® TMOS, 0.2 g of “Karstedt catalyst” (correspondingto 0.0205 mmol of Pt) and 34.38 mmol of methanol were initially chargedin a 0.5 l stirred apparatus with reflux condenser, metering apparatus.At a temperature of 70-87° C., a mixture consisting of 0.33 mol ofTAICROS® and 6.55 mmol of benzoic acid was metered in within 1 hour.Thereafter, the mixture was left to react further at 81° C. for another1 hour. Subsequently, 41.5 g of low boilers were removed at 61-121° C.and a pressure of <0.1 mbar. This gave 183.0 g of Incompletely convertedand colourless bottom product.

Evaluation of the 1H NMR spectrum from Comparative Example 5: Solvent: NCDCl₃ + 0.5% Signal at Number of TMS [ppm] Integral protons I/N % (mol)S1 0.66 100.0 2 50.00 81.5 A1 5.25 21.75 2 10.87 17.7 P1 0.94 1.09 30.36 0.6 I1 1.01 0.38 3 0.13 0.2 Result: 81.5% of the allyl groups wereconverted by hydrosilylation with TMOS trimethoxysilylalkyl groups (cf.S1). 17.7% of the allyl groups (A1) were not converted. 0.6% propylgroups (P1) and 0.2% isopropyl groups (I1) that contaminate the productwere formed. The conversion of the allyl groups is incomplete, and onlya low level of by-products is formed.

Comparative Example 6

0.33 mol (83.1 g) of TAICROS®, 0.2 g of Catalyst No. 1 (corresponding to0.0205 mmol of Pt) and 6.79 mmol (1.7 g) of3,5-di-tert-butyl-4-hydroxybenzoic acid were initially charged in a 0.5l stirred apparatus with reflux condenser, metering apparatus. At atemperature of 91-111° C., 1.2 mol (146.6 g) of Dynasylan® TMOS weresupposed to be metered in. The hydrosilylation is highly exothermic and,after metered addition of 18 g of Dynasylan® TMOS, the temperature hadalready risen from 91 to 97° C. within 9 minutes. Once a further 72 g ofDynasylan® TMOS had been metered in within 27 minutes and thetemperature had risen to 108° C. it was not possible to detect anyexothermicity in the course of further addition of Dynasylan® TMOS. Thereaction mixture cooled down from 108 to 89° C. within a few minutes.The experiment was therefore stopped after metered addition of a totalof 90 g of Dynasylan® TMOS; in other words, the reaction stopped and theconversion in this procedure thus remained correspondingly incomplete.68 g of Dynasylan® TMOS were not metered in.

Note:

The present comparative experiments for preparation oftris[3-(alkoxysilyl)propyl] isocyanurates by hydrosilylation of1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TAICROS®) in thepresence of a Pt catalyst system composed of Pt catalyst and carboxylicacid show that a comparatively low conversion of the double bond of wellbelow 90 mol % is discovered when

-   -   a mixture of H-silane, Pt catalyst, carboxylic acid and TAICROS®        is used, heated and reacted as such    -   H-silane and Pt catalyst are initially charged and heated and a        mixture of TAICROS® and carboxylic acid is metered in    -   H-silane, Pt catalyst and alcohol are initially charged and        heated and a mixture of TAICROS® and carboxylic acid is metered        in    -   H-silane, Pt catalyst, carboxylic acid and alcohol are initially        charged and heated and TAICROS® is metered in or    -   TAICROS®, Pt catalyst and carboxylic acid are initially charged        and heated and H-silane is metered in.

Example 1

0.33 mol of TAICROS®, 0.2 g of Catalyst No. 1 (corresponding to 0.0205mmol of Pt) and 6.79 mmol of 3,5-di-tert-butyl-4-hydroxybenzoic acidwere initially charged in a 0.5 l stirred apparatus with refluxcondenser, metering apparatus. At a temperature of 91-111° C., 0.82 molof Dynasylan® TMOS was metered in within 45 minutes. Subsequently, 33.7mmol of tert-butanol were added and, at a temperature of 96-111° C. 0.38mol of Dynasylan® TMOS was metered in within 20 minutes. Thereafter, themixture was left to react further at about 109-120° C. for about 1further hour. Subsequently, 24.3 g of low boilers were removed at about104-120° C. and a pressure of <0.1 mbar. This gave 204.9 g of completelyconverted and colourless bottom product. As well as the target product,the following trace impurities were evaluated via the ¹H NMR spectra:

Evaluation of the ¹H NMR spectrum of example 1:

Solvent: N CDCl₃ + 0.5% Signal at Number of TMS [ppm] Integral protonsI/N % (mol) S1 0.66 100.0 2 50.00 97.3 A1 5.25 0.02 2 0.01 <0.1 P1 0.942.09 3 0.70 1.4 I1 1.01 2.01 3 0.67 1.3 Result: 97.3% of the allylgroups were converted by hydrosilylation with TMOS to trimethoxysilylgroups. Allyl groups (A1) are still longer detectable in very smallamounts. 1.4% propyl groups (P1) and 1.3% isopropyl groups (I1) thatcontaminate the product were formed. The conversion of the allyl groupsis complete, and only a low level of by-products is formed.

Example 2

0.973 mole TAICROS®, 0.6 g catalyst Nr. 1 (0.0615 mmole Pt) and 19.98mmole acetic acid were placed in a 1.0 l-reactor equipped with stirrer,reflux condenser and dosing device. At a temperature of 72-101° C. 2.33mole Dynasylan® TEOS-H were added within 42 minutes. Subsequently 33.7mmole ethanol were added and at a temperature of 96-111° C. 1.16 moleDynasylan® TEOS-H were added within 25 minutes. The reaction mixture washeated for another hour to 109-120° C. Then 98.2 g low boiler wasremoved at 104-140° C. and a pressure of <0.1 mbar. 718.9 g of acolorless product is remaining in the reactor. The composition of theproduct was analyzed via 1H-NMR analysis:

Results of the ¹H-NMR-spectrum of example 2:

Solvent: N CDCl₃ + 0.5% Signal at Number of TMS [ppm] Integral protonsI/N % (mol) S1 0.64 100.00 2 50.00 98.77 A1 5.26 — 2 — <0.1 P1 0.94 1.483 0.50 0.98 I1 1.06 0.45 3 0.15 0.25 Result: 98.77% of the allylicgroups reacted with the Si-H groups and triethoxysiylalkylgroups wereformed. Allylic groups which reacted to triethoxysilylalkyl groups (S1).Free allylic groups could not he detected (A1). 0.98% of propyl groups(P1)- and 0.25% iso-propyl groups (I1) were formed as impurities. Theconversion of the allylic groups is very high and only small amounts ofimpurities are formed.

Example 3

0.167 mole TAICROS®, 0.1 g catalyst Nr. 1 (0.01025 mmole Pt) and 1.64mmole benzoic acid were placed in a 0.5 l-reactor equipped with stirrer,reflux condenser and dosing device. At a temperature of 86-120° C. 0.4mole Dynasylan® DEMS (methyldiethoxysilane) were added within 42minutes. Subsequently 33.5 mmole ethanol were added and at a temperatureof 96-111° C. 0.2 mole Dynasylan® DEMS were added within 25 minutes. Thereaction mixture was heated for another hour to 106-110° C. Then 12.6 glow boiler are removed at 65-110° C. and a pressure of <0.1 mbar. 108.2g of a colorless product was remaining in the reactor. The compositionof the product was analyzed via 1H-NMR analysis:

Results of the ¹H-NMR-spectrum of example 3:

Solvent: N C₆D₆ + 0.5% Signal at Number of TMS [ppm] Integral protonsI/N % (mol) S1 0.62 100.00 2 50.00 98.18 A1 5.25 — 2 — <0.1 P1 0.75 2.13 0.70 1.37 I1 0.87 0.7 3 0.23 0.45 Result: 98.18% of the allyl groupsreacted with the Si-H groups and methyldiethoxysilylalkylgroups wereformed. Allylic groups which reacted to methyldiethoxysilylalkyl groups(S1). Free allylic groups could not be detected (A1). 1.37% of propylgroups (P1)- and 0.45% iso-propyl groups (I1) were formed as impurities.The conversion of the allylic groups is very high and only small amountsof impurities are formed.

Example 4

0.167 mole TAICROS®, 0.1 g catalyst Nr. 1 (0.01025 mmole Pt) and 1.64mmole benzoic acid were placed in a 0.5 l-reactor equipped with stirrer,reflux condenser and dosing device. At a temperature of 56-80° C. 0.4mole Dynasylan® DMES (dimethylethoxysilane) were added within 40minutes. Subsequently 32.6 mmole ethanol were added and at a temperatureof 96-111° C. 0.2 mole Dynasylan® DMES were added within 25 minutes. Thereaction mixture was heated for another hour to 87-92° C. Then 8.9 g lowboiler are removed at 75-120° C. and a pressure of <0.1 mbar. 95.0 g ofa colorless product was remaining in the reactor. The composition of theproduct was analyzed via 1H-NMR analysis:

Results of the ¹H-NMR-spectrum of example 4:

Solvent: N C₆D₆ + 0.5% Signal at Number of TMS [ppm] Integral protonsI/N % (mol) S1 0.54 100.00 2 50.00 99.7 A1 5.25 — 2 — <0.1 P1 0.75 0.033 0.01 <0.1 I1 0.87 0.4 3 0.13 0.3 Result: 99.7% of the allyl groupsreacted with the Si-H groups and dimethylethoxysilylalkylgroups wereformed. Allylic groups which reacted to dimethylethoxysilylalkyl groups(S1). Free allylic groups (A1) and propyl groups (P1) could not bedetected. 0.3% iso-propyl groups (I1) were formed as impurity. Theconversion of the allylic groups is very high and only small amounts ofimpurities are formed.

The invention claimed is:
 1. A process for preparing atris[3-(alkyldialkoxysilyl)propyl]isocyanurate of the formula:

comprising the following steps: (A) preparing a mixture comprising atleast one carboxylic acid, a platinum catalyst and1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione of the formula:

(B) heating the mixture prepared in step (A) to a temperature in therange of 40° C.-140° C.; (C) adding a hydrosilane of the formula:

to the mixture prepared in step (B); (D) adding at least one alcohol tothe mixture prepared in step (C); and (E) isolating thetris[3-(alkyldialkoxysilyl)propyl]isocyanurate of the formula above. 2.The process according to claim 1, wherein the molar ratio of thehydrosilane to the at least one alcohol is 1:0.005-0.3.
 3. The processaccording to claim 1, wherein the molar ratio of the hydrosilane to theplatinum catalyst is 1:0.000000001-0.0001.
 4. The process according toclaim 1, wherein the molar ratio of the hydrosilane to the at least onecarboxylic acid is 1:0.001-0.03.
 5. The process according to claim 1,wherein the molar ratio of the hydrosilane to1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is 1:0.1-1.
 6. Theprocess according to claim 1, wherein the at least one carboxylic acidis selected from the group consisting of benzoic acid, propionic acid,2,2-dimethylpropionic acid, 3,5-di-tert-butylbenzoic acid,3,5-di-tert-butyl-4-hydroxybenzoic acid and acetic acid.
 7. The processaccording to claim 1, wherein the at least one alcohol is a C₁-C₁₀alcohol.
 8. The process according to claim 1, wherein the at least onealcohol is selected from the group consisting of methanol, ethanol,tert-butanol, benzyl alcohol and diglycol monomethyl ether.
 9. Theprocess according to claim 1, wherein the at least one alcohol isethanol.
 10. The process according to claim 1, wherein the platinumcatalyst is selected from the group consisting of a Karstedt catalyst, ahexachloroplatinum(IV) acid and platinum adsorbed on a solid support.11. The process according to claim 1, wherein the platinum catalyst isselected from the group consisting of aplatinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in theform of a Karstedt catalyst in xylene or toluene with a 0.5%-5% w/wplatinum(0) content, hexachloroplatinum(IV) acid dissolved in acetoneand platinum adsorbed on activated carbon.
 12. The process according toclaim 1, wherein the platinum catalyst is aplatinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in theform of a Karstedt catalyst in xylene or toluene with a 0.5%-5% w/wplatinum(0) content.
 13. The process according to claim 1, wherein theprocess further comprises performing step (C) at a temperature in therange of 86° C.-120° C.
 14. The process according to claim 1, whereinthe process further comprises performing step (D) at a temperature inthe range of 96° C.-111° C.
 15. The process according to claim 1,wherein the process further comprises recovering the platinum catalystfrom the mixture formed in step (D) prior to performing step (E). 16.The process according to claim 1, wherein the process further comprisesperforming step (E) via distillation at a temperature in the range of45° C.-150° C. and at a pressure less than 1 bar.
 17. The processaccording to claim 1, wherein at least 90 mol % of the allyl groups inthe 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione are convertedby hydrosilylation to 3-(alkyldialkoxysilyl)propyl groups.